Farming and the prevalence of non-reversible airways obstruction: results from a population-based study.

INTRODUCTION Occupational exposure to noxious dusts, gases, and fumes most likely contributes to obstructive lung disease. We studied whether self-reported farming work is associated with non-reversible airways obstruction. METHODS Following the burden of obstructive lung disease (BOLD) study protocol, we surveyed a gender-stratified population-based sample of 2,200 adults aged 40 years and over. Pre- and post-bronchodilator spirometry, as well as information on smoking, occupation, and reported respiratory disease was recorded. According to GOLD criteria, non-reversible airways obstruction was defined as a post-bronchodilator forced expiratory volume (FEV(1))/forced vital capacity (FVC) < 0.70. Occupational and smoking history was based on questionnaire. Farming was defined as ever working in this occupation for 3 months or longer. RESULTS For 1,258 participants with complete data (post-bronchodilator spirometry and questionnaire data), 288 (=22.9%) reported farming. Among the 288 participants reporting farming, the prevalence of non-reversible airways obstruction was 30.2%. Farming was significantly associated with airways obstruction: chronic obstructive pulmonary disease (COPD) GOLD stage I or higher (OR 1.5; 95% CI 1.1-2.0) and COPD GOLD stage II or higher (OR 1.8; 95% CI 1.2-2.7). The latter estimate was unchanged when adjustment for competing risks gender, age, and smoking was done. In this population the risk for non-reversible airways obstruction attributable to farming was 7.7%. CONCLUSION Farming should be considered a risk factor for non-reversible airways obstruction.